Process for recovering polymers



June 14, 1960 B. R. TEGGE ETA'- PRocEss FOR RECOVERING POLYMERS FiledMay 15, 1957 mm. wm.

Il wNll/ www Inventors Bruce R. Tegge Johp F. Ryan Lewis D E thermgtonJohn L. Bryan, Jr

By www PROCESS FOR RECGVERING POLYMERS Filed ll/Iay l5, i957, Ser. No.659,302

{CL :i60-85.3)

i7 Claims.

rhis invention relates to improved processes for the production andrecovery of certain homopolyrners and copolymers. More particularly, the`present invention relates to improved methods of dissolving-andprocessing -or product recovery polyisoolefins or copolymers ofisooletins with multiolefins and/or monooleiinic compounds containing acyclic nucleus. The invention `further relates to an improved method ofremoving deposits of such homopolymersk or copolymers from thepolymerization reaction zone in which they were produced.

Broadly stated, `the process of the 'present invention comprisescontacting a lo-W temperature isoolefin containing-homopolyrner orcopolymer slurried in a diluent at a higher temperature with avol-atilized super heated solvent boiling above .the lboiling point ofthe diluent at conditions adapted to volatilize diluent and dissolve atleast a substantial proportion of the polymeric material in the solvent.Other embodiments of the present invention, which will be more fullydescribed hereinafter, comprise 4recycling diluent to form additionalslurry, utilizing a minor proportion of the volatilized solvent inliquid form to periodically Wash an olf stream reactor free of polymeror copolymer, and removing solvent from the polymer or copolymer bymeans of certain higher boiling media with the subsequent recycling ofsolvent in vapor form to produce additional polymer or copolymersolution.

The invention will be best understood by ythe following descriptionwherein reference will be made to the accompanying drawing in which thesingle ligure is a diagrammatic representation in the form of a iiowplan depicting a typical process in Aaccordance with the presentinvention.

By prior art processes, in order to obtain high yields of polymers,polyisoolens or copolymers of isoolens with multiolelins and/ormonooleiinic compounds containing a cyclic nucleus are commerciallyproduced in a diluent which is a non-solvent for the polymer orcopolymer formed, such as C1 to C3 alkyl halides having boiling pointsbelow that of water. When polymerizing C4 to C8 isoolens such asisobutylene, Z-methyl-l-butene, and v3-met'nyl-l-butene or the likealong with minor proporltions of C4 to C14 multiolefins such asisoprene, butadiene, dimethyl butadiene, piperylene, dimethyallyl,alloocymene, cyclo pentadiene, myrcene, vinyl fulvenes or the likeand/or such mono olelinic compounds containing a cyclic nucleus asstyrene, alpha methyl styrene, para methyl styrene, para chloro styrene,dichloro styrene, dihydro naphthalene, indene, etc., the polymerizationreactions are performed at temperatures of below C. 'and preferablybelow about -50 C. downto about 200 .C. The polymer or copolymer whichis produced in Va reaction zone is in the 4form of a slurry inthe alkyl,halide diluent. This slurry is then conventionally causedY to 'flowinto a ilash drum where it 4is contacted with steam ,-to remove volatilematerials and-with hot Water to reslurry the polymer or copolymer inaqueous suspension. The polymeric material is then conventionallyrecovered by filtratiomdegassing extrusion, and drying or the like. Thepolymer or copolymer as recovered has a Staudinger arent molecularweight of between about 2,000 and 1,000,000, advantageously betweenabout 5,000 and 500,000, and preferably between about 10,000 and300,000.

Although best yields of polymer or copolymer of narrow molecular weightdistribution are obtained when the polymeric material is produced as aslurry as outlined above, in many instances the resul-ting dried polymermust be subsequently dissolved in a solvent such as an inert hydrocarbonin order to facilitate the homogeneous blending of Vthe polymer orcopolymer with pigments, oils, waxes, asphalts, lresins,'plasticizers,and the like. Also, where it is desired to chemically modify a polymeror copolymer by halogenation, nitration or the like, such modiiicationsare best performed while the polymeric material is ldissolved in asolvent. However, any known process of dissolving such polymericmaterials is time consuming and expensive. The dissolution time variesdepending `upon the lmolecular weight of the polymer or copolymer from afew minutes up to several hours or more, providing reasonably eflicientagitating, churning'or hornogenizing means are employed.

in accordance with the present invention, there is provided aninexpensive and substantially instantaneous process of dissolving highyields of undissolved polymers or copolymers so vas -to facilitatesubsequent blending with the materials above mentioned or the chemicalmodification thereof. This is accomplished by contacting the polymer orcopolymer slurried at a .temperature of about 100 to 0 C. in the C1 toC3 alkyl halide diluent l(preferably the reactor elfluent slurry) at ahigher temperature, preferably between about .0 and 100 C., with asolvent such as a Cto C10 hydrocarbon which has been vaporized andpreferably super heated to a temperature of between about and 250 C.under conditions adapted to volatilize diluent and dissolve thepolymeric material in the solvent. By thus Vaporizing the solvent, sayto a temperature of about 50 C. (i.e., 90 F.) above its boiling point,the vaporizer exchange area required is only about one-sixth orone-eighth the area of a solution exchanger due to the far bettercoecients of heat transfer vfor the former case.

When practicing the process of the present invention, it is preferred tocondense the alkyl halide vapors formed and recycle the same in theliquid form to the reactor to produce additional slurry. The resultingpolymer or copolymer-.containing solution is then processed in any`desirable manner such as by stripping out unreacted olens,preferablywvithsolvent vapors, and then contacting the olefin-freesolution with a .chemical agent capable of modifying the polymer orcopolymer.

Alternatively the polymer or copolymer-containing solution is blended`with minor proportions of such materials as oils, pigments, waxes,asphalts, resins, plasticizers, etc. The thusmodilied polymer orcopolymer dissolved in Vthe solvent may .then 'be contacted with ahigher boilingsolvent'or non-solvent medium such as an aqueous mediumboiling above the boiling point `of the solvent under conditions adaptedto volatilize the solvent, 4the solvent vvapors formed being superheatedand recycled .in vapor form to dissolve additional polymeric material.`Alternatively, the polymeric ,materialis Iblended while well dissolvedLin the lsolvent with such materials asl oilsWaXes, aspha-lts, resins,or plasticizers; these materials serving as the higher boi-ling medium:to `drive oil :the solvent without the .further additionuofotherrhigher boiling solvents or non-solvents such as water. u

For the purposes ofthe present invention, :thealkyl `halide diluentispreferably auunreactive C., to C3 alk l Yhalide which is a solvent forthe monomerand .catalyst but not forthe .rubbery polymer atpolymerization pou ditions andwhich does not form a complex withtlheicatalyst. Suitable diluents falling within'the foregoing class ofalkyl halides are methyl chloride, methylene chloride, ethyl chloride,ethylene chloride, methyl uoride, ethyl fluoride, ethylene fluoride,l-uoro-Z-lluoroethane, ljiuoro-Z-Zdilluoroethane, perfluoropropane, etc.-The ance with the invention may be rapidly and continuously produced,shipped and stored as a viscous l to 20 weight percent solution in ahydrocarbon solvent, as a rubber cement containing, for example, about20 to 30 weight wax blends have utility in dairyand other waxeswhich.has been found to 'render the asphalt lessbrittle-at'low g alkylchlorides preferably contain one to..two carbonatpercent solids, asoil-extended rubber compositions, or as loins' whereas the preferredalkyl Vfluorides contain one to compositions containing butyl` rubberwith a suitableV three-carbon-atom's. Methyl fluoride, and, for economicliller or pigment dispersed therein. In the case of pigreasons, vevenmore especially methyl chloride are the ment addition aud/or oildispersion, the process of the `prefer-red alkyl halides. i inventioneliminates time consuming' and expensive batch- Suitable hydrocarbonsolvents include C4 to C10, ad- 10 wise kneading of butyl rubber with apigment or oil ina vantageously C5 to C9, preferably C6 to C8hydrocarbons Banbury mixer or on a rubber mill. vThe resulting butylsuch as normal or iso-parathns including'butane, hexane, rubbercompounded with pigments and/ or oils is also a heptane-octane,isohexane, isooctane;` naphthenes such more homogeneous composition ofsuperior quality for as cyclohexane and methyl cyclohexane; aromatic.hydrouse in tires, hosing, insulation, rubber window channels, carbonssuch as benzene, toluene andlxylenes; monooleetc. .hns such'ashexenes,'heptenes, octenes; hydrocarbon frac- Also, while it has beendiicult in the past to extend i tions or hydrogenated hydrocarbonfractions such' as very high molecular weight butyl rubber withplasticizers naphthas, Vgasolinesstraight run mineral spirits; verylightV such as oils, tars, waxes, organic phosphates, or resins;fractions of cracked gas oil or kerosenes; mixtures thereaccording toVthe process ofY the present invention, any of, etc.Y Preferredsolventsinclude substantially satudesired degree of such oil extension israpidly -accomrated. hydrocarbons such as heptane, hexane, isooctane,plished since thebutyl rubber is in solution. This higher cyclohexane,benzene, hydrogenated naphthas and hyproportion of plasticizer oilresults in distinct technical drogenated gasolines.

Y and Yeconomical advantages. For instance, oil Yextenln one embodimentof the present invention, polyis'osion of the rubber decreases theproduct cost since oil olens and especially polyisobutylene havingaStaudinger 25 is much cheaper than butyl'rubber.A Furthermore, oil.molecular weight between about 5,000 and 30,000, and eXtenSiOll O fhigh molecular weight butyl rubber greatly preferably between about10,000 and 25,000 are desirably increases vabrasion resistance-ascompared to high mo- --produced Yas a slurry in a diluent,Vthe'diluent being r e. lecular weight butyl rubber perfse. Oftenheretofore, placed by a hydrocarbon solvent and this hydrocarbon v Yoilextension of high molecular weight butyl rubber (e.g., solvent beingvolatilized' while the polyisoolen is being 30, viscosity averagemolecular weight above about 800,000) .'homogeneously blended Vwith ahigher boiling medium has been accomplished by hot milling Which greatlyde' such as a Vmineral lubricating` oil. The same general Y gradedthemolecular weight of the rubber into a lower Y l process applies tothe-'addition of copolymers of isoole- VInoleelllal, Weight Polymer Oiladdilionfin aeenl'danee tins withrminorproportions, preferably about 10to 40 With'the invention, prior to removal ofthe' butylrubber 4-weightpercent based oncopolymer, of Ia vinyl aromatic 35 sloventreduces thisdegradation or breakdown. Vhydrocarbon such as styrene to minerallubricating oils. Similar advantages are derived from the addition of Inboth cases, the polymer or copolymerV serves as a PigmenS,-Snlfn1`, ZineOXde-mneS, IaCCeleraOIS t0 Vvaluable V. I. limprover and isadvantageously added tothe alkyl halide flash drum. Suitable pigmentsinclude alubricating oil predispersed' as a concentrationv in a rel eYCarbon blacks, Silica, hydrated SilieaS Slleh 21S H-Sl 202,Aatively'smau kamount of lubricating oi1'by the Yblending 4- Clays, oto.Resin-tackiers Such as urea-aldohydo resins, 'process hereinbeforedescribed. phenolic-aldehyde type resins (such as a resorcinol for-.Pressure sensitive tapes'and adhesive plasters may also. meldehyderesin) 0I Phenol dialeOhOl resins, Orlhe like, L be made frompolyisoolensor isoolelin-vinyl aromatic `are also; advantageously addedto butyl rubber dissolved hydrocarbon copolymers having Staudingermolecular Y lnaCCOrdanCe With the-present invention. weighrs'betweenlabout 10,000 and 1,000,000 dissowed 4*". The production of abutylrubber latex in accordance '.fin AC5 to Cm hydrocarbonsin. the manner`disclosed in With the invention iS else advantageous- The hlltylFubaccordance with the present invention. Also, blends of Y bel'-diSSOlVed in Ihe hydrOCaIbOn in the alliyl halide flash about l5 to 40weight percent of polymers or copolymers drum may bePIOeeSSed into eneInnlSiOn by an iIlVel'SOIl having molecular weights of between about30,000 and o technique in Which al1 emulsfel and Water are added toY120,000 with about to 85 weight percent of parain 5 the I'nhhel'ybntyllolymer SOlllOn t0 form a water-inwax'may be obtained in accordancewith the present in- Pnlynlel' eInnlSOn Which-i5 then inverted Vi0 aPOlynler-invention by replacing the polymerization diluent with a wateremulsion by the further addition of water. The C5 to C10 hydrocarbon andreplacing this hydrocarbon emulsiers useful in accordance with theinvention may with the higher boiling paran wax, Such polymer and 55 beof the non-ionic, anionic or cationic type; The nonionic emulsiers foundYmost useful are the poly oxyalkenated alkyl phenols or alcohols havingthe formula VR(OCIIR1CHR1)OII where R is an alkyl, aryl, alkaryl Yor.aralkyl group, R1 being an alkyl group or hydrogen and n being aninteger of about 4 to l0 or higher. The alkene oxide units shouldrepresent at least about.40% s of the total molecular weight` of thecompound. These compounds areprepared by condensing an alkyl phenol oranalcohol with a lower alkylene oxide such as ethylene oxide or propyleneoxide. The anionic emulsiliers useful -for the purposes of the presentinvention include such materials as sodium lauryl sulfatethe sodium saltof the i .sulfonatesof the poly oxyethylated alkyl phenols, Vvsodium areY,resistant to'cr'acking at low temperatures.

"It is also within the purview ofY the present invention to blend about0.05 to `5.0, and'preferablyabout 0.5 toi V-.3.0 parts by weight ofpolyisoolefms or copolymers of 60 isooleiins and minor proportions ofsay about 10 to 40 .weight percent of vinyl aromatic hydrocarbons withabout 95 to 99.95weightpercent and preferably -about 97 to 99.5 weightpercent of asphalt. The inclusion of such small amounts of homopolymersor especiallycopolymers *temperatures and tougheratf-high temperatures.l2 The procedure Yin accordancewith the present invennon 'alsofacilitates 'theV rapid and uniformiadditionlof oleyltavrato, vfattyacid soaps of alkali metals; etc,

oils and pigments to high yieldsiof rubbery copolymers The cationicemulsierswhich are' particularly useful ."ofisoolelins and multiolenssuch as butyl rubber since fo the PnlvPOSeS of the-invention includealkyl dimethyl fthe copolymers-are dissolved in solvents. vThe process'benzyl ammonium'chloridegvdisobutyl phenoxy-ethoxyof'the inventionfurthermore facilitatesthe continuous ethyl dimethyl benzyl ammoniumchloride, 'dimethyl i production and processing of extremely highmolecular Vphenoxy-ethoxyethyl dimethylbenzyl ammonium chloride, Weightbutylvrubber. Butyl rubber, produced in accord- 7:5V etc. .The amount ofthe emulsier is generally between aaaaeeo about 0.2 and 15.0 weightpercent, preferably between about 0.5 and 5.0 weight percent, based onpolymer.

A particularly advantageous emulsifying combination is an admixture ofabout 0.5 to 5.0 parts by weight each of potassium oleate, hydrolyzedpolyvinyl alcohol, and a poly oxyethylated alkyl phenol sold under thename of Triton X400.

The butyl rubber solution, before homogenizing into a latex, isadvantageously concentrated (if necessary) to about l to 50, preferablyto about 20 to 30 weight percent polymer content by heating and/orflashing olf sufficient hydrocarbon solvent. The concentrating stepminimizes forming difficulties in subsequent emulsion strippingoperations. It is also preferred to concentrate the butyl rubbersolution as above-mentioned before mixing with the emulsiers, and forthis reason their addition is preferably in a zone removed from thealkyl halide ash drum.

The resulting mixture, containing butyl rubber dissolved in ahydrocarbon solvent, water, and emulsiliers, is then preferably pumpedinto a conventional mixing means or dispersator, generally of theimpellor type, to give a crude emulsion. This crude emulsion is then fedto a highly efficient mixing machine such as a colloid mill or a sonicmixer (e.g., a Rapisonic Hornogenizer). This emulsion is either recycledthrough the homogenizer a number of times or fed consecutively to about2 to l0 homogenizers to obtain a fine emulsion of the desired stability.The emulsion from the last homogenizer stage is pumped to a hydrocarbonvolatilizing means, preferably about l to 5 evaporators known as'furba-Film evaporators for removal of the hydrocarbon solvent and someof the water whereby a latex of the desired concentration is obtained.The resulting latex generally contains about 30 to 70 weight percent,preferably about 40 to 60 weight percent (eg, 50 weight percent) butylrubber. The aforesaid evaporators are generally operated at temperaturesof between about 100 and 220 F. and under about l to 2O p.s.i.a.pressure to obtain maximum capacity for evaporation. The latex productformed is advantageously stored in agitated tanks equipped with meansfor heating and cooling for winter and summer operations. At least aportion of the carbon black or other filler used for compounding priorto vulcanization may also be added to the butyl rubber latex. Thisaddition makes subsequent carbon black addition easier and results inbetter overall carbon black dispersion.

In order to more fully illustra e the present invention, the followingexperimental data are given. Referring now in detail to the drawing, theapparatus shown is suitable for the process of the present invention.There are provided at least two (eg. two to ve) polymerization reactors,namely, reactors l and 66, each equipped with stirrers 2 and 68, carriedon shafts 3 and 70 respectively. A polymerizable feed comprising anadmixture of about 85 to 99.5 weight percent (eg, 98 weight percent) ofa C4 to C8 isoolefin such as isobutylene of at least 98% purity (eg, 99%purity) and about 0.5 to l5 weight percent (e.g., 2.0 weight percent) ofa C4 to C10 conjugated multiolefin such as isoprene of at least about90% purity (e.g., 95% purity) is continuously charged to reactor l viaconduit 5 along with about l to 5 volumes (e.g., 3 volumes) of a C1 toC3 alkyl halide such as methyl chloride. Simultaneously, a solution of aFriedel-Crafts catalyst dissolved in a C1 to C3 alkyl halide (e.g., 0.2weight percent of aluminum chloride in methyl chloride) is charged toreactor 1 via conduit 6. The concentration of the catalyst is maintainedin the reactor at between about 0.01 to 0.50 weight percent andpreferably between about 0.05 to 0.20 weight percent (c g., 0.10 weightpercent) based on total monomers by suitable regulation of the amount ofrecycled methyl chloride diluent to conduit 5 via conduit 8. Theconversion of monomers to rubbery copolymer is maintained at about 50 to90% and preferably at about 70 to 80% (eg, 75%) by controlling the abovefeed to catalyst ratio. The polymer product quality is controlled bymaintaining the polymerization temperature at a level of between aboutto 120 C. (i.e., 120 to 180* F.) and preferably between about and 107 C.(i.e., 130 to 160 E), e.g., C. (i.e., 140 F). The reaction is carriedout either under vacuum, pressure or atmospheric conditions, the generalrange advantageously being from about l0 to about 250 p.s.i.a. (e.g., 30p.s.i.a.), the pressure being preferably regulated to a level of betweenabout' 5 and 50 p.s.i. above the Vpressure in llash drum 53 (e.g., apressure of 10 p.s.i. above the pressure in the tlash drum).

After completion Yof the reaction, va slurry of about 15 to 30 weightpercent, preferably'about 17 to 25 weight percent (c g., 18 weightpercent) of butyl rubber in methyl chloride is then overflowed fromreactor 1 via conduit 7 to ash drum 53 which is ttedrwith an agitator16. Flash drumv 53 is maintained as will appear hereinafter, atatemperature'level suiciently highV to vaporize the methyl chloridediluent and generallyat a pressure of between about 5 and 50 p.s.i.below the pressure in reactor 1. For instance,vash drum .53 isadvantageously operated at temperaturespof between about 0 and 250 F.,preferably between about and 160 F.: (e.g., F.) and at pressures ofbetween about atmospheric pressure and 200 p.s.i.g. (e.g., 5 p.s.i.g.).Simultaneously a superheated C5 to C10 hydrocarbon or mixture of suchhydrocarbons (eg, hexane) is injected in vapor form into ash drum 53 viaconduits 9, 78, and 7. More particularly, hexane in liquid form isconveyed through conduit 9 past valve 72 through valve 74 intovaporizersuperheater 76 where the hexane is vaporized and super-l heatedto 300 F. This superheated vapor is then lpassed through line 78 intoconduit 7 where it contacts the reactor eluent stream and is conveyedwith said stream into llash drum 53 wherein the hexane vapor condensesVgiving oftl sucient heat to volatilirze methyl chloride which is drivenoff overhead via conduit 15 as more fully described hereinafter. Y

The hydrocarbon solvent such as hexane may contain about O to 500 partsper million and especially 30 to 100 parts per million of water (e.g.,50 parts per million of water), ie., sufficient water to deactivate thecatalyst. Alternatively, a small amount of an oxygenated hydro carbonsuch as an alcohol (e.g., isopropanol) or water may be either blendedwith the solvent vapor or injected directly into ash drum 53 to preventafter polymerization. As beforementioned, the flash drum is maintainedat a lower pressure than the pressure in the reactor. This is to forcethe slurry of butyl rubber copolymer in the methyl chloride from thereactor to the ash drum. Flash drum 53 may optionally be heated by anysuitable heat exchange means such as a heating coil in the lower part ofthe ash drum (not shown) or the pump-around heat exchange system asshown which comprises outlet conduit 10, pump 11, conduit 12, heatexchanger 13, and inlet conduit 14. However, it is to be expresslyunderstood that when using the hydrocarbon solvent in vapor form,preferably superheated to the degree hereinbefore mentioned, noauxiliary or additional heat exchange equipment of any type is normallyneeded in order `for flash drum 53 to operate eciently.

The temperature and pressure in flash drum 53 are regulated whereby toash olf a sufficient amount of methyl chloride diluent via conduit 15 tocause the butyl rubber copolymer to dissolve at a rapid rate in thehydrocarbon solvent such as hexane. About 70 to 100% (e.g., 85%) of themethyl chloride is generally removed. The butyl c conduit 1.9 via line22.

Alternatively, for chemical modification, it is highly preferred and inYsome cases necessary to remove unsaturated materials other-than thepolymer. In this case, the dissolved butyl rubber copolymer may bewithdrawn via Vliue117 andintroduced near the `top Yof a 20 to 50 plate(e.g., 25 plates) polymer stripping column (not shown) f wherein Vthepolymer solution passes down the Ycolumn ,counter-current toupwardly'rising solvent vapors, pref- ;-erably supplied to thebottomof.; the column from an external source. VThe solvent vapors mayoptionally be su- Zfrperheated, if desired, to a temperature .insucientto causeV thermal degradation V4of the Y polymer, generally up toVnot'rmor'e than about 50 F. Vsuperhfeat. The 'vaporA leaving tlle'topof lthe column contains, in additiorito Y solvent stripping vapors,unsaturated hydrocarbons such las unreacted monomer and'esrsentially allremaining 'alkyl halide'diluengif any.. The solvent' vaporsY usedl'orystrip-k ping may be obtained at leasf'ixipartV byfseparating out.the unsaturatedhydrocarbons andalkyl halide fromy the overhead products,thetessentially pure-solvent remaining being recycled lin vapor formtothe bottom of the Y polymer stripping column as the stripping medimn.`Y

e Several advantages result Vfrornthe operation describedY Y above.v.,Degradationgof polymermolecular Weight is avoided by obviating theneces'sity'for contacting the poly.

mer Asolution with a heatingv medium in 'indirectheatvexchange-therewith.Y Also, arsubstantialV reduction in Vheatexchange surfaceV required results since the procedureoutlinedaccomplishes the stripping ,operation Ywithout re-Y Vquirng the polymersolution'to be heat transfer equipment. t t

heated in conventional The Y essentially .'oleiinfree polymer?solution', Y with- Y, drawn from the bottom of the polymer strippingcolumn,

maybe then chemically modified while dissolved inthe solvent'orrthesolutionvmay be cooled rand/.013 concen- `trated if necessary -prior tochemical mo'dication. pThis is advantageously accomplished byintroducingthe Vessentially olefin-free polymer solution, withdrawn fromthe polymer stripping column, into a ashzone maintained at a pressuresubstantiallylower than the pressure' in tbe polymer strippingcolumn(e'.'g.',Y atmosphericv pressure) whereby cooling. andconcentration Ysimultaneously occur [due to the evaporation of Vaportion of the solvent. Al-

which `'is -likewise equipped withtagitator 30, low pressure 'steamconduit' 31'and overhead vacuumsteam jet recovery conduit 32.vStripperf29is' advantageously operated at about 120'to 160 F.V (e.g.,140-F.) and at about 2 to Y6 p.s.i.a. (e.g., 4 p.s.i.a.). 'The stripperserves to remove ythe last traces of hexane from the butylrubber-waterslurry'V and return Vthe samev to .hydrocarbon v.flash drum via conduits32 and 33. The watergslurry [of butyl rubber is thenjvithdrawn viaconduit34jand Ypumped bygpump 35 through conduit`36 to variouscon--ventional butyl rubber inishing'operation's, c g., ltering,

extruding', drying, etc.

, .The heXaneior other hydrocarbon solvent, ,inlaccordance with theprocess of the present invention, is recovered from flash drum 20 vialineV 26 through condenser 44 to separator 45. In separator 45 theheavier Awater layer is settled out via conduit 46. Residual methylchlo- T T-he alkyl halide diluent such covered viaY line 15'1byoptionally compressing the va- 4ride vapors, if any, are vented throughline 47. Y'I'he remainingmaterial which Vis substantiallypurehydrocarbon ,solventgenerally containing aboutr30 to 100 parts perVmillion of Water- (e.g., 50 parts per million of water),

is recycled via conduit 48 through pump 49 and conduit 9 past valve 72through valvet74 into ,vaporizer-superheater 76. VIn superh'eater 76,the hexane vapor is'superheated 140 F., i,e-tto a temperaturel level of300 F.,

' V'and passedvia line 78 through conduit back in toalkyl halide flashdrum 53. V f y Y,

as'r'nethyl chloride is repors in a rst stage compressor 54 to about 25to 100 p.s.i.g. (e.g., 50 psig.) discharge pressure, optionally ryingthe alkyl halide by Yintroducing the same via conduit V55 to aluminadrier 56 and'optionally again compressing lthe alkyl halide to about 150to 175 =p.s.i.g.'(e.g., 165 p.s.i.g. in a second stage compressor'57.Alternatively, alkyl halide ash' drum 53 is maintained under suicientpressure that the alkyl halide VdiluentV vapors are readily condensed bycooling .Water in indirect heat vexchange therewith, thereby eliminatingthe necessity of compressors 54 and 57. In such a ease, while `thepressure in theV alkyl halide flashrdrum' 53 is at least about 5 to 570p.s.i. lower than vthe Vpressure inthe re- Y actor, the pressure in Itheflash drum is also regulated to ternatively, at least `a portion ofthestripping vaporsrmay be obtained from ash drum 20, as more fully.described hereinafter. i

' In any case, the solution of butyl rubber polymer or t other polymerorcopolymer in accordance Vwith the present invention which has beenblended with pigments, oils,

waxes, asphalte, resins, plasticizers or the like or chemically'modiedis then introduced into hydrocarbon tiash t t drum 20 via conduit 19.This solution generally contains about 2 to 2O weight percent,preferably about 5 Yto 15 Weight percent (e.g., 10 weightV percent) ofvdissolved rubl bery copolymer. 1 As the butyl rubber solution entersliash drum 20 via conduit 19, it is preferably steam atomat about 180 F.and l5. p.s.i.g. The vaporized'hyd'rocarbon suchras hexane is withdrawnvia;conduit26andis recovered as more fully described hereinafter. In -an.optional but Vpreferred embodiment,` additional e lowpresv` sure steamis alsofinjec'ted into hydrocarbon flash drum Y 20 via conduit 27. t t

` The resulting water slurry of butylfrubber generally contains aboutlto'5 weight percentpolymer (e.g.,' 2.0 weight percent polymer) and'iswithdrawn from hydro- :fcarbon dash drum 20 via Aconduitv 28j to'vacuumstrippen Y plates (e.g.,V 50 plates).

is Vsubstantially pure methylY chloride.

a pressure of at least between about 15 and 200 p.s.i.g. (e.g., about 50p.s.i.g.). lIn Ithis latter instance, the alkyl halide such asmethylchloride may be recovered via line 15 conduit 50, condenser 51, line-52,conduit 55, drier 56, conduit 58, second stage compressorY 57, Vandconduit Y38 into fractionating column or tower 37. A portion (e.g., 20weight percent of the total) of the alkyl halide vapors condensed incondenser 51 may be returned in liquid Vform via conduit V61 to ash drum53 as recycle to enrich the overhead vapor stream in alkyl halidepassingout conduit 115.* Alternatively, the alkyl halide may berecovered via line 15, conduit 50, condenser 51, line V59, conduit 53,second stage compressor 57, and conduit 38' into fractionating column ortower 37 or merely through` conduits 15, 60 and 38 into fractionatingvcolumn or tower 37. t

In any case, they resulting alkyl halide stream is introduced intofractionating column or tower' 37 via conduit 38. VFractionating columnor tower 37 may-be fitted with a -reboiler and may contain about 20 to100 It desirably has a reflux ratio of between about 5 `to l and l5 tol(e.g.9 to l). The

Y Vmjerheacl productV comprises 'about 5 to 2'5 Vweight perpercent(e.g., 10 weight percent of the towerV 1feedY and Y ThisV f overheadproduct is recycled via overhead conduit'39 to catalyst inlet conduit 6leading to reactor 1 afterthaving'been Vblended with a Vdesired amountof aluminumfchloride catalyst Yfromjconduit 40. The bottomsrfrom`fraction-V ating columns 37 are fed into secondV fractionating column41 via conduit 42. Fractionating column `41 con- `tains between about l0and 40 plates (e.g., kZtlplates) and operates at a reiiux ratio of about0.5 to l and 3 to 1 (e.g., 1.5 to 1). The major proportion of the methylchloride diluent is then withdrawn from fractionating column 41 viaoverhead conduit 8 and mixed with fresh monomer to be charged via line 5to reactor 1. The alkyl halide leaving ractionating column 41 via line 8contains about 3 to 8 Weight percent (e.g., 5 weight perpercent of C4unsaturates such as isobutyiene. The bottoms from fractionating column41 are then introduced via conduit 43 to a 30 to 70 plate strippingcolumn, e.g., a 50 plate stripping column (not shown), from which asmall amount of methyl chloride (eg, 1 weight percent based on thetotal) is recovered and recycled to conduit 8. The stripper bottoms arenow free of methyl chloride and comprise additional amounts (e.g., lweight percent based on the total) of C4 hydrocarbons which areconventionally purged as well as unreacted isoolen (e.g., isobutylene)and multiolelin (c g., isoprene) monomers. The unreacted isobutylene andisoprene are then recovered (after additional fractionation to split thestream into each respective material) by conventional isobutylene andisoprene units respectively.

During the time when reactor 1 is on stream as mentioned above, reactor66 is off stream and is being cleaned as more fully describedhereinafter. More particularly, a portion (e.g., 20 weight percent ofthe total hexane vapors are passed through valve 72 into condenser 30where .the vapors are condensed but maintained at a temperature level ofbetween about 100 and 150 F. (e.g., 130 F.) The hot hexane liquid thenpasses through conduit 62 past closed valve 84 through open valve S6into reactor 66 Where the hexane dissolves butyl rubber occluded on thesurfaces of the reactor and passes the same via conduit 88 into line '7leading into the alkyl halide flash drum S3. After about 2O to 50 hours(e.g., 35 hours), the reactor surfaces of reactor 1 will have becomesuiciently occluded or fouled with polymer deposits that it will bedesirable to conduct the polymerization reaction in reactor 66 placingreactor 1 off stream for cleaning. At this time, valves 86, 90, 92, 94and 104 are closed and valves S4, 96, 98, 100 and 102 are opened inorder to place reactor 66 on stream. Reactor 1 is then olf stream and iswashed by hot hexane from conduit 82 through valve 84, the dissolvedrubber formed being passed through valve 100 into conduit 38 leadinginto line 7 and introduced int-o the alkyl halide liash drum 53.

It has been observed that when practicing the processes of the presentinvention in accordance with this example, that the rubbery copolymer isdissolved much more rapidly than has ever been possible heretofore.Also, plugging of control valves with ice and methyl chloride hydrateshave not been experienced. Analysis of recycle catalyst streams haveshown negligible amounts of such reaction poisons as hydrochloric acid,methyl alcohol and dimethyl ether. that by the use of vapor hexanesubstantial savings in heat transfer equipment are obtained.Furthermore, the above described wash system to remove occludedcatalysts from off stream reactors has proved a quick and eiective meansof not only cleaning the reactor but of saving both rubbery polymer andsolvent.

Resort may be had to modiications and variations of the disclosedembodiments without departing from the spirit of the invention or thescope of the appended claims.

What is claimed is:

1. In a process for continuously dissolving isooleiincontainingpolymeric materials in solvents, said polymeric materials being selectedfrom the group consisting of homopolymers of C4 to C8 isoolens,copolymers of C4 to C isoolens with C4 to C14 multioleiins andcopolymers of C4 to C0 isoolefns with a vinyl aromatic hydrocarbon, thecombination which comprises contacting a It has also been observedslurry of said polymeric material in a C1 to C3 alkyl halide non-solventliquid reaction diluent with an inert C5 to C10 hydrocarbon solvent invapor form, which, when condensed in liquid form is a solvent for thepolymer, to volatilize the non-solvent diluent and condense the solventvapor to dissolve the copolymer in the solvent.

2. A process according to claim l in which the polymeric material is ahomopolymer of a C4 to C0 isoolen.

3. A process according to claim 1 in Which the polymeric material is arubbery copolymer of a C4 to C0 isoolefin and a C4 to C14 multiolen.

4. A process according to claim 1 in which the polymerio material is acopolymer of a C4 to C0 isoolen and a vinyl aromatic hydrocarbon.

5. A process according to claim 1 followed by condensing and recyclingof the vaporized C1 to C5 alkyl halide non-solvent diluent in liquidform to produce additional polymer slurry.

6. In a process for continuously recovering isoolencontaining polymericmaterials by the use of solvents, said polymeric material being selectedfrom the group consisting of homopolymers of C4 to C8 isoolens,copolymers of C4 to C0 isoolens with C4 to C14 multiolens and copolymersof C4 to C5 isoolens with a vinyl aromatic hydrocarbon, the combinationwhich comprises contacting a slurry of said polymer in a C1 to C3 alkylhalide non-solvent liquid diluent with a C5 to C10 inert hydrocarbon invapor form, which, when condensed in liquid form, is a solvent for saidpolymeric material, to volatilize the non-solvent diluent and dissolvethe polymer in the C5 to C10 hydrocarbon solvent, and subsequentlyvaporizing said hydrocarbon solvent.

7. A process according to claim 6 in which the polymeric material isbutyl rubber, a rubbery copolymer of a major portion of a C4 to C5isoolen and a minor portion of a C4 to C10 multiolen.

8. A process according to claim 6 in which the polymeric material ispolyisobutylene.

9. A process according to claim 6 in which the polymeric material is acopolymer of isobutylene and styrene.

10. A process according to claim 6 in which the vaporized C5 to C10hydrocarbon solvent is recycled to volatilize additional C1 to C3 alkylhalide non-solvent liquid diluent.

11. A process according to claim 6 in which the C5 to C10 hydrocarbonsolvent is vaporized by contact with a vapor of a liquid having aboiling point higher than said C5 to C10 hydrocarbon solvent.

12. A process according to claim 11 in which the higher boiling liquidis Water.

13. A process according to claim 1l in which the higher boiling liquidis oil.

14. A process according to claim 6, followed by contacting the solutionof polymeric material with additional C5 to C10 hydrocarbon solventwhich has been superheated to a temperature level of about to 250 C. invapor form to remove any unreacted monomer whereby to form anessentially olefin-free solution of polymeric material.

15. A process according to claim 14 in which the polymeric material isbutyl rubber, a rubbery copolymer of a major portion of a C4 to C8isoolen and a minor portion of a C4 to C10 multiolein.

16. A process according to claim 14 in which the polymeric material is acopolymer of isobutylene and styrene.

17. A process according to claim 14 in which the essentially olen-freepolymer-containing solution is subsequently contacted with ahalogenating agent.

References Cited in the le of this patent UNITED STATES PATENTS2,843,761 Rose et al. May 13, 1958

6. IN A PROCESS FOR CONTINUOUSLY RECOVERING ISOOLEFINCONTAININGPOLYMERIC MATERIALS BY THE USE OF SOLVENTS, SAID POLYMERIC MATERIALBEING SELECTED FROM THE GROUP CONSISTING OF HOMOPOLYMERS OF C4 TO C8ISOOLEFINS, COPOLYMERS OF C4 TO 8 ISOOLEFINS WITH C4 TO C14 MULTIOLEFINSAND COPOLYMERS OF C4 TO C8 ISOOLEFINS WITH A VINYL AROMATIC HYDROCARBON,THE COMBINATION WHICH COMPRISES CONTACTILNG A SLURRY OF SAID POLYMER INA C1 TO C3 ALKYL HALIDE NON-SOLVENT LIQUID DILUENT WITH A C5 TO C10INERT HYDROCARBON IN VAPOR FORM, WHICH, WHEN CONDENSED IN LIQUID FORM,IS A SOLVENT FOR SAID POLYMERIC MATERIAL, TO VOLATILIZE THE NON-SOLVENTDILUENT AND DISSOLVE THE POLYMER IN THE C5 TO C10 HYDROCARBON SOLVENT,AND SUBSEQUENTLY VAPORIZING SAID HYDROCARBON SOLVENT.
 11. A PROCESSACCORDING TO CLAIM 6 IN WHICH THE C5 TO C10 HYDROCARBON SOLVENT ILSVAPORIZED BY CONTACT WITH A VAPOR OF A LIQUID HAVING A BOILING POINTHIGHER THAN SAID C5 TO C10 HYDROCARBON SOLVENT.